I used to make 3D models and moving 3D gifs in Photoshop all the time, but now I can't access any 3D workspace/extrusion options in Photoshop CS5. I'll go to the Window drop down menu and 3D isn't even listed (as opposed to being in the list but unclickable/greyed out). I need to do some 3D modeling for an upcoming project but don't know how to get those options available to me again. Help!!

I checked GPU settings, everything seems good there. it's the same machine, although i did accidentally uninstall photoshop and had to reinstall it a little while back so i'm pretty sure therein lies the problem, i just have no idea how to go about fixing it. i'm scared to deinstall and reinstall again because i don't have the physical software/CD anymore, nor the serial number, and it was a real pain in the *** to reinstall the program because of that. honestly i don't even remember how exactly it got resolved but somehow i got photoshop back, but without 3d capabilities. im assuming this means i don't have the extended version anymore? how can i get that again?

and yea i guess "all the time" was hyperbole, meaning several times a week for about two years.

You say you don't have the original discs or the serial number.Presumably, you installed the Standard version instead of the Extended version.You will need to find your original Serial Number - you can't buy CS5 (any version) anymore - if you want to get your Extended version working again.

Beware too - the version you are currently running sounds like it is an illegal copy.

I would advise subscribing to PS CC ($9.99 a month - extremely cheap at the price).